The availability of electronic means has reduced the delay between
acceptance and
publication of papers in refereed journals from 6-10 down to 3-6 months
(or even 1 month in case of letters or short communications),
largely because authors prepare their own manuscripts electronically
in the formatting requirements of the journals. Nevertheless, for conference
proceedings the figure remains between 10 and 20 months. Such a delay
did (and still does) crucially affect certain types of research. Thus,
for several decades, the ``remedy'' to this delay has been
a frequent exchange of preprints among astronomers,
and until very recently, the preprint shelves used to be the most
frequented areas in libraries.
This situation has gradually changed since April 1992, when both SISSA
(International School for Advanced Studies, Trieste, Italy) and LANL
(Los Alamos National Laboratory, USA)
started to keep mirror archives of electronically submitted preprints
(xxx.lanl.gov). In the
first years of their existence, preprints
were dominant in the fields of theoretical cosmology and particle
physics, and about 35 astro-ph preprints were submitted monthly
in mid-1993. The popularity of this service has increased impressively
since then: over 60,000 daily accesses to
xxx.lanl.gov from
6,000 different hosts (see Fig. 3), and
about 300 preprints submitted per month in 1997/8 only
for astro-ph (and ~ 1800 altogether), with a fair balance
between all parts of observational and theoretical astrophysics;
mirror sites have been installed in 12 other countries (Australia,
Brazil, China, France, Germany, Israel, Japan, Russia, South Korea,
Spain, Taiwan, and the UK, see
xxx.lanl.gov/servers.html).
A further mirror site is under construction in India. References to
electronic preprints from LANL/SISSA are made more and more frequently in
refereed journals, and the LANL/SISSA server also provides links to
citations to, and references from, their electronic preprints to other
preprints of the same collection.

Figure 3. Daily accesses to the LANL
preprint server. The regular 2-day dips are weekends, while the wider
dips are due to Thanksgiving, Christmas and New Year 1997/98.

You may subscribe to receive a daily list of new preprints.
To avoid this flood of emails you could rather send an email
to astro-ph@xxx.lanl.gov just
after the end of month mm of
year yy, with subject ``list YYMM'' , e.g. ``list 9710'',
to receive a full list of preprints archived in October 1997.
To get the description of all the functionalities of the preprint
server (e.g. how to submit or update your own preprints), send an
email to the above address with ``Subj:get bighelp.txt''.
If you want to check for the presence of a certain preprint, send an
email with ``Subj:find keyword'' , where keyword is an author
or part of the title of the paper. You need to add a year if you want to
search further back than the default of one year from the current date.
Once you have located the preprint(s) that you are interested in, the most
efficient (least time-consuming) method to obtain a copy is to request
it by its sequence number YYMMNNN, via email to the same address with
Subj:get YYMMNNN. It comes in a self-extracting uuencoded file
which you need to save in a file, say XYZ, strip off the mail header,
and just execute it with the command csh XYZ. A common shortcoming is that
authors sometimes do not include all necessary style files with their papers.
Generally these can be obtained separately from the server by email
with Subj: get whatever.sty. Another solution to this problem is
to use the web interface at xxx.lanl.gov/ps/astro-ph/YYMMNNN,
where (unlike the email or ftp service)
the complete PS files of papers are indeed available (and are in fact
created on the fly upon request).

Submission of a preprint to the LANL/SISSA server is today the most
efficient way of world-wide ``distribution'' without expenses for
paper or postage, since the preprint will be available to the entire
community within 24 hours from receipt, provided it passes some technical
checks of file integrity and processability. Note, however, that
electronic preprint servers contain papers in different stages
of publication: accepted, submitted to a refereed journal or to appear
in conference proceedings. Occasionally the authors do not explain the
status of the paper, and the preprint server may have been
the only site to which the paper has ever been submitted.
Of course, a reference made to a preprint of work that was never
published should be regarded with caution in case it was subsequently
rejected by a journal. Note also that
only a fraction of all papers published in refereed journals (perhaps
30-50% now) is available from LANL/SISSA prior to publication.
Many other preprints are offered from web pages of individual researchers
or from institutional pages.
A substantial collection of links to other sources of preprints is
provided at www.ucm.es/info/Astrof/biblio.html#preprints.

You can also check a list of ``Papers Submitted to
Selected Astrononomical Publications'' at
www.noao.edu/apj/ypages/yp.html. A list of papers
submitted to the Astronomical Journal can be viewed at
128.95.99.33/ajcgi/papers. Note that these
are submitted and not necessarily accepted articles.
The pages come with links to email the authors, which is very helpful if
you wish to ask some of them for a copy.
There is also a page with ``Titles and abstracts of ApJ Letters
accepted but not yet published'' at
cfa-www.harvard.edu/aas/apjl_abstracts.html.

A ``Distributed Database of Online Astronomy Preprints and Documents''
is currently in the early stages of development. While not functional as
yet, there is a web page describing the project. People wanting to monitor
progress, or make suggestions, are invited to look at the URL
doright.stsci.edu/Epreps.